For a more complete understanding of the embodiments, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: In a conventional Package-on-Package (PoP) processes, a top package is bonded to a bottom package. The top package and bottom package may also have device dies packaged therein. By adopting the PoP process, the integration level of the packages may be increased.
In an existing PoP process, the bottom package is formed first, by placing a device die over a release layer, wherein the release layer is over a carrier. A plurality of through-assembly vias (TAVs) is formed over the release layer, and the release layer is formed over a carrier. The device die and the plurality of TAVs are then molded in a molding compound and the molding compound is then cured. Due to shrinkage of the molding compound following the step of curing, stress from the cured molding compound and the TAVs may cause the device die to delaminate from the release layer.